System for controlling a transfer clutch of a fourwheel drive vehicle

Claim 2

A control system for a four-wheel drive vehicle having an engine, a transmission, main drive wheels operatively connected to an output shaft of the transmission, auxiliary drive wheels, a transfer clutch for transmitting the output of the transmission to the auxiliary drive wheels, and means for controlling torque of the transfer clutch in accordance with driving conditions of the vehicle, the system comprising: detector means for detecting speed ratio of front-wheel speed and rear-wheel speed and for producing a speed ratio signal; means for determining that the speed ratio signal represents steering operation of the vehicle and for producing a steering angle signal dependent on the speed ratio signal; control means responsive to the steering angle signal for controlling the torque of the transfer clutch so as to slip the transfer clutch in dependence on the steering angle signal.

Claim 3

A control system for a four-wheel drive vehicle having an engine (E), a transmission (A), main drive wheels operatively connected to an output shaft (11) of the transmission (A), auxiliary drive wheels, a transfer clutch (22) for transmitting the output of the transmission (A) to the auxiliary drive wheels, and means (60, 33) for controlling torque of the transfer clutch (22) in accordance with driving conditions of the vehicle, the system comprising: means (62, 62) for detecting the speed of the main wheels and of the auxiliary wheels; means (66) for producing a speed ratio signal from the detected main and auxiliary wheel speeds; means (67, 68, 69) responsive to the speed ratio signal for producing a steering angle signal dependent on the speed ratio signal when it is within a range representing steering operation; control means (70, 71, 33) responsive to the steering angle signal for controlling the torque of the transfer clutch (22) so as to allow the transfer clutch to slip in dependence on the steering angle signal.

Claim 4

A control system for a four-wheel drive vehicle having an engine (E), a transmission (A), main drive wheels operatively connected to an output shaft (11) of the transmission (A), auxiliary drive wheels, a transfer clutch (22) for transmitting the output of the transmission (A) to the auxiliary drive wheels, and means (60, 33) for controlling torque of the transfer clutch (22) in accordance with driving conditions of the vehicle, the system comprising: means (62, 62) for detecting the speed of the main wheels and of the auxiliary wheels; means (66) for producing a speed ratio signal from the detected main and auxiliary wheel speeds; means (67, 68, 69) responsive to the speed ratio signal for producing a steering angle signal dependent on the speed ratio signal when it is within a range representing steering operation; control means (70, 71, 33) responsive to the steering angle signal for controlling the torque of the transfer clutch (22) so as to allow the transfer clutch to slip in dependence on the steering angle signal.

Claim 5

A control system as claimed in claim 1 or 2, wherein there is means (69) for determining the slipping of the main drive wheels on the basis of the speed ratio signal and for producing a slipping signal, and the control means (70, 71, 33) being responsive to the slipping signal for increasing the torque of the transfer clutch.

Claim 6

A four-wheel drive vehicle comprising: an engine (E), a transmission (A), main drive wheels operatively connected to an output shaft (11) of the transmission (A), auxiliary drive wheels, a transfer clutch (22) for transmitting the output of the transmission (A) to the auxiliary drive wheels, and means (60, 33) for controlling torque of the transfer clutch (22) in accordance with driving conditions of the vehicle, and a system as claimed in any preceding claim.